There are currently 41 IAS and 9 IFRS. Although not all of the ISAs are still used as they superseded by other standards and made outdated.
The AAR is good capital budgeting tool because managers can compare it to objective benchmarks. Yet one limitation is that ARR uses profit rather than cashflows, and it does not account for the time...
International accounting standard board is responsible for standards more information at http://www.iasb.org/Home.htm
I know that in international accounting LIFO and eaxtrordinary items are prohibited
Here is a link to a great paper by from the SEC , outlining the major differences in International Accounting Standards.